This invention relates to the type of wind turbine which rotates at high speed and has a horizontal shaft and few blades in general and more particularly to an improved pitch regulation drive for such a turbine.
Because of the nature of wind power, which is characterized by varying wind speeds with relatively high amplitudes, wind power stations must be equipped with means for limiting variations in power and for limiting the force on the blades to moderate values.
In large wind power stations, at least, this limiting is provided by making the turbine blades such that they can twist about their longitudinal axes, so that the angle of twist or pitch angle may be varied to suit variations in wind speed.
For such stations known in the art, pitch regulation is generally accomplished by an electronic-hydraulic system, where the required motive power is obtained from hydraulic cylinders placed in the rotating turbine hub. This location of the hydraulic cylinders creates severe technical problems. These problems are allied to the fact that the whole of the hydraulic system, including cylinders, valves and accummulators, rotates with the turbine and must be connected to the stationary system via means permitting such rotation.
Considerable difficulties also occur in inspection and maintenance, since it is difficult to provide access to the hub of the turbine in a wind power stations.
For these reasons, several other solutions have been proposed and tried. One object here has been to have the motive power required for twisting the turbine blades provided by a power source having a more protected and accessible position inside the plant.
A simple and reliable structure is also an object, since such plant is usually unmanned and remotely controlled.
Solutions proposed so far have not satisfied these demands, however, and have furthermore involved other drawbacks, such as considerably increased length of machinery, and they have therefore not inspired any confidence in their reliability.
It is thus the object of the present invention to provide a solution to this problem.